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1.
EPMA J ; 8(2): 111-117, 2017 Jun.
Article in English | MEDLINE | ID: mdl-28725291

ABSTRACT

BACKGROUND: Besides intraocular pressure, vascular factors play a role in the pathogenesis of glaucomatous optic neuropathy. One of these potential vascular factors is Flammer syndrome. The purpose of the present study was to determine in a Korean population whether signs and symptoms of Flammer syndrome occur more often in normal tension glaucoma patients than in control subjects. METHODS: Two hundred forty-six normal tension glaucoma patients and 1116 control subjects responded to a multiple-choice questionnaire asking about 15 signs and symptoms of Flammer syndrome. RESULTS: Seven of the 15 signs and symptoms of Flammer syndrome (increased drug sensitivity, good smell perception, reversible skin blotches, tinnitus, long sleep onset time, tendency to perfectionism, and cold hands/feet) were significantly more often positive in normal tension glaucoma patients than in controls. Six additional signs and symptoms (migraines, low blood pressure, headaches, dizziness, increased pain sensation, and feeling cold) also occurred more often, but did not reach statistical significance. Only two items (low body weight and reduced feeling of thirst) were more frequently (not significant) positive in the controls. CONCLUSION: There is an association between normal tension glaucoma and Flammer syndrome. If future studies confirm this relationship, treatment of Flammer syndrome may help to prevent normal tension glaucoma or to slow down its progression.

2.
Rom J Ophthalmol ; 60(2): 79-89, 2016.
Article in English | MEDLINE | ID: mdl-29450328

ABSTRACT

PURPOSE: Photon-correlation spectroscopy (PCS) (quasi-elastic light scattering spectroscopy, dynamic light scattering spectroscopy) allows the non-invasively reveal of local dynamics and local heterogeneities of macromolecular systems. The capability of this technique to diagnose the retinal pathologies by in-vivo investigations of spatial anomalies of retinas displaying non-exudative senile macular degeneration was evaluated. Further, the potential use of the technique for the diagnosis of the macular degeneration was analyzed and displayed by the Receiver Operating Curve (ROC). METHODS: The maculae and the peripheral retina of 73 normal eyes and of 26 eyes afflicted by an early stage of non-exudative senile macular degeneration were characterized by time-correlation functions and analyzed in terms of characteristic decay times and apparent size distributions. RESULTS: The characteristics of the obtained time-correlation functions of the eyes afflicted with nonexudative macular degeneration and of normal eyes differed significantly, which could be referred to a significant change of the nano- and microstructure of the investigated pathologic maculas. CONCLUSIONS: Photon-correlation spectroscopy is able to assess the macromolecular and microstructural aberrations in the macula afflicted by non-exudative, senile macular degeneration. It has been demonstrated that macromolecules of this disease show a characteristic abnormal behavior in the macula.


Subject(s)
Dynamic Light Scattering , Geographic Atrophy/diagnosis , Spectrum Analysis/methods , Aged , Female , Humans , Macula Lutea , Male , Middle Aged , ROC Curve , Visual Acuity
3.
Cornea ; 32(2): 165-8, 2013 Feb.
Article in English | MEDLINE | ID: mdl-23187160

ABSTRACT

PURPOSE: The depth of corneal crosslinking (CXL) does not seem homogeneous within the treatment area but shows a reduction toward the periphery of the cornea. This study was undertaken to investigate this reduction effect and to look for possible solutions. METHODS: Ten corneas were investigated by means of an optical coherence tomography system (SS-100; Tomey, Nagoya, Japan) 1 month after standard CXL (epithelium off, 0.1% riboflavin for 30 minutes, ultraviolet A radiation 365 nm, 3 mW/cm). The depth of the demarcation line was measured as a function of the radial distance from the apex. These curves were compared with a theoretical curve derived from a standard model of photopolymerization. RESULTS: The CXL depth 3 mm away from the center decreases on average to 65% of the central depth (range: 52%-78%). Polymerization theory predicts this decay, however, underestimates the effect. CONCLUSIONS: The intended depth of CXL using current light sources is achieved only within the central area of the cornea. To provide CXL to the peripheral cornea, the ultraviolet beam either should have an improved intensity profile or may have to be decentered.


Subject(s)
Collagen/metabolism , Corneal Stroma/metabolism , Keratoconus/drug therapy , Photosensitizing Agents/therapeutic use , Riboflavin/therapeutic use , Ultraviolet Rays , Cornea/pathology , Cornea/radiation effects , Corneal Pachymetry , Cross-Linking Reagents/therapeutic use , Follow-Up Studies , Humans , Keratoconus/metabolism , Permeability , Polymerization , Tomography, Optical Coherence , Visual Acuity/physiology
4.
Acta Ophthalmol ; 90(3): e173-8, 2012 May.
Article in English | MEDLINE | ID: mdl-22336219

ABSTRACT

PURPOSE: To explore the molecular alterations of the vitreous by dynamic light scattering (DLS) spectroscopy (quasi-elastic light scattering spectroscopy, photon-correlation spectroscopy) in normals and in patients afflicted with various degrees of non-proliferative and with proliferative diabetic retinopathy. METHODS: Dynamic light scattering spectroscopy was employed to analyze the vitreous of normals and of patients with diabetes non-invasively to estimate both the sizes and diffusion coefficients of mobile macromolecules and/or microparticles. RESULTS: Abnormal molecular behaviour of vitreous molecules was observed in patients with diabetes afflicted with various degrees of diabetic vitreo-retinopathy. In the non-proliferative (background) retinopathy, both the diameters of the microparticles increase and the diffusion constants decrease significantly and progressively as the diabetic disease progresses. In the proliferative phase, a significant trend in the direction of smaller particles and greater diffusion constants is evident. These behaviours could also be interpreted as an increase in the viscosity of the intermolecular substance in the first case and as a decrease in the second. CONCLUSIONS: The vitreous in normals and even more so in diabetics with diabetic vitreo-retinopathy is optically a highly non-isotropic, multidispersive structure, making an optical analysis difficult. Advanced, but available models and technology, however, permits a major step forward in the optical analysis of the normal and the diseased vitreous.


Subject(s)
Diabetic Retinopathy/metabolism , Multiprotein Complexes/metabolism , Photoelectron Spectroscopy , Vitreous Body/metabolism , Aged , Female , Fluorescein Angiography , Humans , Light , Male , Middle Aged , Scattering, Radiation , Visual Acuity/physiology
5.
Technol Health Care ; 16(6): 445-59, 2008.
Article in English | MEDLINE | ID: mdl-19212040

ABSTRACT

An analysis and mathematical comparison of models underlying the phenomena of brightness and contrast are presented. The concept of self-excitation which has not so far been considered is introduced into the structure of the models. Mach Bands can be described by two essentially different but formally identical mechanisms. The phenomenon allows neither a functional explanation in terms of models presented heretofore nor an answer to the question whether data processing is based in the human visual system on integrating of differentiating of on both.


Subject(s)
Models, Neurological , Sensory Thresholds/physiology , Visual Perception/physiology , Contrast Sensitivity/physiology , Humans , Light , Linear Models , Photic Stimulation
6.
Technol Health Care ; 15(4): 247-58, 2007.
Article in English | MEDLINE | ID: mdl-17673834

ABSTRACT

OBJECTIVE: To detect post-op molecular changes and inflammatory processes by dynamic light scattering (DLS) in eye segments. To develop DLS parameters which are appropriate for the control of post-op course after ophthalmologic surgery. METHODS, DESIGN: Three new DLS devices were tested in different post-op clinical settings such as pseudoexfoliation syndrome (PEX), cataract surgery and retinal surgery. In a second step DLS was used to detect molecular changes in the cornea of 6 patients after photo refractive keratectomy (PRK) and 16 patients after photo astigmatic refractive keratectomy (PARK). RESULTS: In PEX-patients cataract surgery changed the DLS signals of the anterior chamber and the lens in a specific way compared to the pre-op situation. Cataract patients without PEX had more scattering particles post-op and retinal surgery modified the DLS signal of the vitreous. Furthermore it was shown that the length of the corneal scattering vector l correlated with the process of the corneal wound healing after PARK. One and three months after surgery the lengths of the scattering vectors had increased significantly but returned to pre-op values twelve months post-op. DISCUSSION: The post-op transparency of eye segments such as the cornea, the vitreous and the anterior chamber depends primarily on the wound healing mechanisms. DLS seems to be a suitable method to control the corneal recovery after refractive surgery. CONCLUSIONS: The length of the scattering vector l correlates well with the wound healing after refractive surgery. However DLS-signals seem to contain information about the molecular composition of tissue too. Therefore further research is needed to refine the interpretation of the DLS signals.


Subject(s)
Cornea/physiopathology , Lens, Crystalline/physiopathology , Refraction, Ocular , Vision, Ocular , Vitreous Body/physiopathology , Adult , Aged , Case-Control Studies , Cataract/physiopathology , Cataract Extraction , Corneal Topography , Equipment Design , Exfoliation Syndrome/physiopathology , Exfoliation Syndrome/surgery , Follow-Up Studies , Humans , Inflammation/physiopathology , Inflammation/surgery , Laser Therapy , Lasers, Excimer , Middle Aged , Ophthalmology/instrumentation , Photorefractive Keratectomy , Postoperative Period , Retinal Detachment/physiopathology , Retinal Detachment/surgery , Treatment Outcome
8.
Technol Health Care ; 14(6): 521-35, 2006.
Article in English | MEDLINE | ID: mdl-17148865

ABSTRACT

OBJECTIVE: To calibrate new dynamic light scattering (DLS) devices in defined solutions and post mortem porcine and human eyes. To examine all segments of the eye and to become familiar with the usage of the technique in living subjects. METHODS, DESIGN: Three new DLS devices for the usage in patients were developed. Mono-disperse solutions, poly-disperse solutions, gels, post mortem porcine and human eyes as well as healthy volunteers were studied. The detected signals were inverted into autocorrelation functions. RESULTS: We constructed three DLS devices appropriate for in vitro as well as in vivo examinations. In mono disperse solution precise disintegration rates could be calculated. In poly-disperse solutions, in gel and in the vitreous the results did not correlate with movements of individual particles but we could calculate characteristics of the complete scattering system. In vivo measurements demonstrated that DLS can be used in all human eye segments. DISCUSSION: DLS is a unique technique. With DLS the molecular composition of eye segments can be studied in living subjects. This can be used to understand the molecular basis of severe eye diseases. The presented data demonstrate that DLS delivers reproducible data from all eye segments. CONCLUSIONS: It is possible to study the molecular structures of eye segments in living subjects. The developed devices were proved successfully in vitro as well as in vivo. Limitations are the low specificity of DLS and its sensitivity to background noise. Now clinical studies are necessary to demonstrate potential diagnostic benefits of DLS in specific eye diseases.


Subject(s)
Ophthalmology/instrumentation , Ophthalmology/methods , Refraction, Ocular , Animals , Humans , Swine
9.
Ophthalmologica ; 219(3): 123-8, 2005.
Article in English | MEDLINE | ID: mdl-15947496

ABSTRACT

The program Perisim 2000 enables one to simulate the interaction of a number of visual field examination strategies with a number of stored visual fields, both normal and pathological, with several patterns of observer (patient) behavior. A considerable number of visual fields, patient behavior patterns and examination strategies, including a full bracketing strategy, Gonzalez de la Rosa's tendency-oriented perimetry (TOP) and Weber's dynamic program, are available. Statistical programs are also incorporated. While the examination strategies to be used in the simulations must be selected from a predefined list, new visual field and observer patterns may be defined by the user. The results may be shown as numerical tables, symbolic or gray tone, pseudocolor or profile displays. Cumulative defect curves may also be selected. The learning/teaching benefits of the program Perisim 2000 are considerable. It is easy to understand and to operate, and ample explanations are available at each step of the program.


Subject(s)
Computer Simulation , Visual Field Tests/methods , Visual Fields , Humans
10.
Appl Opt ; 44(11): 2162-76, 2005 Apr 10.
Article in English | MEDLINE | ID: mdl-15835362

ABSTRACT

A variety of optical and electro-optical instruments are used for both diagnostic and therapeutic applications to the human eye. These generally expose ocular structures to either coherent or incoherent optical radiation (ultraviolet, visible, or infrared radiation) under unique conditions. We convert both laser and incoherent exposure guidelines derived for normal exposure conditions to the application of ophthalmic sources.


Subject(s)
Eye Injuries/prevention & control , International Agencies/standards , Ophthalmoscopes/adverse effects , Ophthalmoscopes/standards , Radiation Injuries/prevention & control , Radiation Protection/standards , Risk Assessment/standards , Eye Injuries/etiology , Guidelines as Topic , Humans , Light/adverse effects , Models, Biological , Ocular Physiological Phenomena/radiation effects , Radiation Dosage , Radiation Injuries/etiology , Radiation Protection/methods , Radiometry/methods , Radiometry/standards , Risk Assessment/methods
11.
Ophthalmologica ; 218(3): 147-61, 2004.
Article in English | MEDLINE | ID: mdl-15103211

ABSTRACT

Methods used in laser destructive procedures are detailed. While in noncontact procedures laser energy is delivered via the optics of a slitlamp, often enhanced by contact lenses, the contact method takes advantage of optical fibers for the delivery of energy. Endpieces such as hemispherical or microlens probes enhance the cyclodestructive effect and/or allow the dose of laser energy to be reduced. Laser energy may also be delivered under direct view by endoscopic systems. Advances in laser cyclodestruction are possible by studying the physical effects.


Subject(s)
Ciliary Body/surgery , Laser Coagulation , Animals , Biophysical Phenomena , Biophysics , Endoscopes , Endoscopy , Equipment Design , Fiber Optic Technology , Humans , Laser Coagulation/instrumentation , Miniaturization , Optical Fibers , Sclera
12.
Ophthalmologica ; 218(2): 77-95, 2004.
Article in English | MEDLINE | ID: mdl-15004496

ABSTRACT

Laser cyclophotocoagulation is an accepted method of cyclodestruction, such as cyclocryothermy and the application of cyclodiathermy, microwaves and ultrasound. These procedures may be considered as ultima ratios or 'last-resort interventions'. Also, in cases where surgery is not possible, cyclodestruction may be the initial intervention. Among other lasers, the Nd:YAG and diode lasers are the energy sources of choice. Contact and noncontact methods have about the same clinical efficiency and risk. While immediate complications are transitory, other, late complications, mentioned in the world literature, such as sympathetic ophthalmia, malignant glaucoma and retinal detachment, are more serious but are rare, and their causal relationship with the cyclodestructive procedure is doubtful. However, they still merit our attention. The ultrastructural mechanisms related to cyclocoagulation have been studied. The study of aqueous flow may improve our understanding of cyclophotocoagulation techniques. Cyclophotocoagulation is considered an important cornerstone in glaucoma therapy. The uncertainty of its effect is no greater than that of any other therapeutic measure in the treatment of glaucoma.


Subject(s)
Ciliary Body/pathology , Ciliary Body/surgery , Glaucoma, Open-Angle/surgery , Ophthalmologic Surgical Procedures , Aqueous Humor/metabolism , Diathermy , Glaucoma, Open-Angle/pathology , Humans , Intraocular Pressure , Laser Coagulation , Microwaves , Ultrasonic Therapy
13.
Technol Health Care ; 12(6): 443-53, 2004.
Article in English | MEDLINE | ID: mdl-15671599

ABSTRACT

Wavelength-corrected, adaptive optics and their relevance for diagnostic procedures of the human retina are considered. First, it is shown that the compensation of errors of the dioptric apparatus of the eye allows sharp and high-contrast images of retinal elements, such as the photoreceptors, to be generated. This technology is expected to enable on the one hand an improved laser therapy by the application of laser spots of the size of single receptors as well as on the other a further understanding of the mechanisms of vision, in particular of colour vision by using colour stimuli not larger than the cones. Second, femtosecond laser pulses, emitted from lasers working in the near infrared, based on multiphoton effects allow both imaging and laser effects to be generated which are in the submicron range and which do not cause collateral damage (nanoimaging and nanosurgery). These procedures, related to experimental ophthalmology may be considered a milestone for the research of cell physiology, in particular in the subcellular range.


Subject(s)
Biomedical Technology , Cornea/surgery , Retina/diagnostic imaging , Visual Acuity/physiology , Humans , Radionuclide Imaging
14.
Ophthalmologica ; 217(1): 1-16, 2003.
Article in English | MEDLINE | ID: mdl-12566866

ABSTRACT

The clinical effects of the Nd:YAG laser operating in both the photodisruptive (Q-switched) and thermal (free-running, cw) modes are discussed, and their clinical applications investigated. Moreover, the physical background of the working modes is explored. When working in the photodisruptive and fundamental (TEM(00)) modes, it is possible to carry out delicate clinical tasks with minimally invasive effects. When the laser is being used in the multimode regime, tasks that are highly resistant to photodisruptive laser radiation can be undertaken. In the thermal mode, photocoagulation can be performed. Nd:YAG laser light (1,064 nm) has high optical tissue penetration and good hemostatic properties, particularly when it is being operated in the frequency-doubled mode (KTP laser).


Subject(s)
Anterior Eye Segment/surgery , Eye Diseases/surgery , Laser Coagulation/methods , Ophthalmologic Surgical Procedures , Adolescent , Adult , Aged , Anterior Eye Segment/pathology , Eye Diseases/pathology , Female , Humans , Male
15.
J Refract Surg ; 19(1): 52-7, 2003.
Article in English | MEDLINE | ID: mdl-12553607

ABSTRACT

PURPOSE: To demonstrate a technique of anterior lamellar keratoplasty with standardized and automated preparation of surface-parallel cuts in both donor and recipient appropriate for addressing several problems after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). METHODS: We report a noncomparative series of ten eyes with complications after LASIK and PRK. Lamellar cuts were performed in donor and recipient eyes by means of an automated microkeratome. Lamellar grafts were fixed by only four single sutures. In two eyes, a re-lift LASIK was performed after 6 months. RESULTS: Surgery was uneventful and visual acuity was improved in all eyes. Residual irregular astigmatism and refractive error were corrected in two eyes by means of excimer laser computer-assisted ablation and resulted in a further improvement of uncorrected and best spectacle-corrected visual acuity. CONCLUSIONS: Anterior lamellar keratoplasty with a microkeratome can be used for the management of certain complications of PRK and LASIK.


Subject(s)
Cornea/surgery , Corneal Diseases/surgery , Corneal Transplantation/methods , Keratomileusis, Laser In Situ/adverse effects , Photorefractive Keratectomy/adverse effects , Postoperative Complications , Adult , Cornea/pathology , Corneal Diseases/etiology , Corneal Topography , Female , Humans , Lasers, Excimer , Middle Aged , Postoperative Complications/surgery , Refractive Surgical Procedures , Treatment Outcome , Visual Acuity
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